Hg is very portable as it is 95% Python and 5% C for speed. Hg also runs on Windows.

git is mostly a collection of C and shell, and has been ported to just about everything. There are a couple of tools in perl that may be of interest for the base system (which we would have to rewrite), a few in python that won't be, and one in tk that is definitely out. So, we shouldn't have any modula3-like issues, and should also be able to avoid bringing in any new scripting languages, including perl.